This invention pertains to surgical systems and, more particularly, apparatus and methods for attaching sutures and soft tissue to bone. The invention has application in, for example, the reattachment of tendons and ligaments to bones, such as in procedures to repair anterior cruciate ligaments or to repair torn rotator cuffs.
It is not uncommon for tendons and other soft tissues to tear or to detach from bone. One injury common to athletes, for example, is a "rotator cuff" tear, in which the supraspinatus tendon separates from the humerus, causing pain and loss of ability to elevate and externally rotate the arm. Another common injury is an anterior cruciate ligament (ACL) tear, in which one of the ligaments connecting the femur and the tibia is ruptured. Surgeons are routinely called upon to reattach tendons and other soft tissues to bone in remedying these and other injuries.
One difficulty of such surgery is anchoring tissues or sutures to bone in a manner capable of withstanding the normal stresses of movement. An early procedure, which is still in use, involves sewing the tissue directly to bone by passing a suture through a hole in the bone. This method presents the risk of bore hole migration, i.e., migration of the suture through the sides and edges of the bone hole, especially when used in the weaker bone of older patients.
Metal screws, pins, staples, and other such "anchors" provide an alternative means for affixing soft tissue to bone. While metal offers strong holding ability, especially in hard bone, its use has associated disadvantages including corrosion, metal sensitivity in the patient, and interference with sophisticated imaging techniques such as magnetic resonance imaging. Moreover, the substantial force required to drive metal anchors into bone may cause additional damage.
Many of the problems associated with metal can be mitigated by the use of plastic or bioabsorbable anchors. However, non-metallic anchors typically do not possess the holding power of metal and may also be more fragile.
Among the prior art non-metallic anchors is Hayhurst, U.S. Pat. No. 4,741,330, which describes a suture anchor having a generally bullet-shaped resilient plastic member having a rounded convex base from which wings extend. The wings, which are provided with outward-pointing barbs on their outer surface, diverge radially outward when the member is in a relaxed state. The member is compressed and inserted into a predrilled bone hole, then allowed to relax so that its resilience splays the wings outward against the bone wall. The anchor is set by applying tension to the suture, causing the edges of the wings and the surface barbs to dig into the bone. The anchor is marketed by Acufex Microsurgical and commonly referred to as the "wedge."
An object of the present invention is to provide improve methods and apparatus for anchoring objects, such as sutures, tendons, and soft tissues, to bone.
Another object of the present invention is to provide a bone anchor of simple design and construction.
Another object of the present invention is to provide a bone anchor design suitable for use with a range of biocompatible materials, including metals, plastics and bioabsorbables.
Another object of the present invention is to provide methods and apparatus for anchoring objects to bone which require substantially no impact or impulse required in the emplacement process.